What Girls Said 1
1. She hangs around when you are there and doesn't make excuses to leave.2. She smiles at you a lot and makes eye contact.3. She asks you a lot of questions about yourself.These are some of the signs that you should wath for.
What Guys Said 1
I'd say if she isn't returning your letters, or communicating with you at all, she doesn't have the same feelings. Relationships should always be balanced. If she's into you, she'll make every effort to see that you don't slip out of her reach (in most cases). I'd say let her go, as painful as it might be, and seek out other girls to date and have fun with, and eventually you'll find one who's into you as much as you're into her. It's not the end of the world. Actually, it's the beginning. Best of luck man.